This project will study electrical brain-activity measures that may be able to indicate whether or not long-term memory is occurring, under light sedation. The goal is to develop a brain-monitor to be used in the operating room to ascertain if a patient's level of anesthesia has become too light, such that the patient can experience pain, and understand what is occurring in the operating room, and remember the experience. Such an event is rare, but traumatic. No present brain-analysis system accurately distinguishes the boundary in light anesthesia, between that level in which there will be explicit-memory and that level in which explicit-memory is missing. The fundamental scientific goal is to provide a tool for further investigations of the mechanisms of explicit memory, in animals as well as humans. If the goal were achieved, it would offer the chance to develop a clinical tool for analysis, diagnosis, or prognosis of medical conditions involving changes in memory (for which present tools are often inadequate). The project is health-related in that it addresses a problem in clinical medicine, and will provide a solution to that problem, if successful. PUBLIC HEALTH RELEVANCE: This project is relevant to public health because it studies humans and their reactions to sedation under anesthetic agents, to find a way to detect whether, in an operation, the patient is alert enough to remember experiences. This is a rare event in surgery, but should be prevented, if possible, with the techniques that will be developed in this research.